This invention relates to quality control of manufactured parts and, more particularly, to a method of automatically marking parts to facilitate inspection and rework of the part.
Quality control of manufacturing processes involving the machining of parts typically requires that some percentage of each batch of parts be pulled and inspected for nonconformity with design dimensions. Such inspection requires that actual part dimensions be measured for comparison with design tolerances. The number of measurements required depends on the complexity of the overall geometry of the part and of the particular surfaces involved. When the measurements indicate that a portion of a machined surface is out-of-tolerance on one or more of the inspected parts, a decision must be made whether to pass, rework or scrap the out-of-tolerance part(s). Moreover, a decision must be made regarding the parts of the batch that have not been inspected. Specifically, the operator must make a determination as to whether some or all of the non-inspected parts are likely to exhibit the out-of-tolerance condition. This can result in an entire batch being scrapped or unnecessarily reworked.
To add to the problem, the inspection/decision process must be repeated for each machining operation required to manufacture a part. Thus, if the procedure requires that 5% of the parts be inspected after each manufacturing process, a batch of 100 parts requiring five machining operations to produce will require 25 time-consuming inspections.
This approach is not only costly, it leaves the potential for discrepant parts to make it through the process undetected. The only way to avoid this problem and to make six sigma quality possible is to inspect every part. Using current methodologies this approach is entirely impractical
An embodiment of the present invention provides a method of marking on a surface of a part a graphical representation of deviations of the surface of the part from a design standard for the surface. The method comprises determining a point deviation for each of a plurality of points on the surface. The method further comprises determining deviation regions for the surface. Each deviation region includes only surface points having point deviations within a predefined deviation range associated with the deviation region. The method also comprises preparing a graphical representation of the surface illustrating the deviation regions and applying a copy of the graphical representation to the surface.
The step of determining point deviations in a method according to the present invention may include determining a measured point position relative to a fixed reference frame for each of the plurality of points. The step may further include determining from the design standard an expected point position relative to the fixed reference frame for each of the plurality of points and calculating the point deviation for each of the plurality of points using the measured point position and the expected point position. The step of determining a measured point position relative to a fixed reference frame may include positioning the part in a fixture at a predetermined orientation. This step may further include capturing at least one digital image of the surface and processing the at least one digital image in a data processor to determine the measured point positions of the plurality of points.
The steps of determining an expected point position, calculating a point deviation for each point, determining deviations regions for the surface, and preparing a graphical representation in a method according to the present invention may be carried out by a data processor. The method may further comprise displaying the graphical representation on a graphical user interface.
Another aspect of the invention provides a method of marking on a surface of a part a graphical representation of deviations of the surface from a design standard for the surface. The method comprises positioning the part in a fixture at a predetermined orientation, capturing at least one digital image of the surface, and downloading the at least one digital image to an automatic data processing system. The method further comprises processing information from the at least one digital image to determine a measured point position for each of a plurality of points on the surface. The method also comprises determining from the design standard an expected point position relative to the fixed reference frame for each of the plurality of points. A point deviation is calculated for each of the plurality of points using the measured point position and the expected point position. The method still further comprises determining deviation regions for the surface, each deviation region including only surface points having point deviations within a predefined deviation range associated with the deviation region. The method also comprises displaying a graphical representation of the surface illustrating the deviation regions on a graphical user interface and applying a copy of the graphical representation to the part surface.
The deviation regions determined in methods according to the present invention may be assigned a unique color for use in illustrating the deviation region in the graphical representation of the surface. The step of applying a copy of the graphical representation to the machine surface may include painting on the surface a representation of each deviation region using the color assigned to the deviation region.
Methods according to the present invention may further comprise identifying deviation regions that include points with deviations that exceed predetermined tolerance criteria. The methods may further include reworking the surface in response to identification of deviation regions that include points with deviations exceeding the predetermined tolerance criteria. The copy of the graphical representation applied to the surface may be used as a guide for reworking the surface.
One aspect of the present invention provides an inspection system for inspecting and marking a surface of a part. The system comprises a measurement station having means for obtaining spatial position data relative to a fixed reference frame for each of a plurality of points on the surface. The system further comprises a data processing system in communication with the means for obtaining spatial position data. The data processing system has means for receiving the spatial position data and for determining a point deviation from a surface standard point for each of at least a portion of the plurality of surface points. The data processing system also has means for preparing a graphical representation of a deviation map of the surface. The system further comprises a marking station having means for marking a copy of the graphical representation on the surface of the part. The means for marking is in communication with the data processing system.
Another aspect of the invention provides an inspection system for inspecting and marking a surface of a part. The system comprises a measurement station including a measuring system configured to obtain spatial position data relative to a fixed reference frame for each of a plurality of points on the surface. The system further comprises a data processing system in communication with the measuring system. The data processing system includes a mapping module programmed to use the spatial position data to form a three-dimensional map of the surface. The data processing system also include a deviation determination module programmed to determine a point deviation for each of at least a portion of the plurality of surface points. The data processing system also includes a deviation map module programmed to construct a graphical representation of a deviation map of the surface. The inspection system further comprises a marking station including an image transfer system in communication with the data processing system. The image transfer system is configured to mark a copy of the graphical representation on the surface of the part.
Yet another aspect of the invention provides an inspection system for inspecting and marking a surface of a part. The system comprises a measurement station including a measurement system configured to obtain spatial position data relative to a fixed-reference frame for each of a plurality of points on the surface. The system further comprises a data processing system in communication with the measuring system. The data processing system includes a mapping module programmed to use the spatial position data to form a three-dimensional map of the surface. The data processing system further includes a deviation determination module programmed to determine a point deviation for each of at least a portion of the plurality of surface points. The data processing system still further includes a deviation map module programmed to construct a graphical representation of a deviation map of the surface. The data processing system also includes a graphical user interface for selected display of the graphical representation. The inspection system also comprises a marking station include an image transfer system in communication with the data processing system. The image transfer system includes a printing arrangement having a remotely controllable printing applicator. The printing arrangement is configured for application of the graphical representation to the surface.
Still another aspect of the invention provides an inspection system for inspecting and marking a surface of a part. The system comprises a fixture configured to secure the part in a predetermined orientation with respect to a fixed reference frame and an optical-based meteorology arrangement having at least one digital imaging device. The digital imaging device is configured to obtained at least one digital image of the surface of the part for use in obtaining spatial position data relative to the fixed reference frame for each of a plurality of points on the surface. The inspection system also comprises a data processing system in communication with the at least one digital imaging device. The data processing system includes a mapping module programmed to use the at least one digital image to determine spatial position data for each of the plurality of points on the surface and to form a three-dimensional map of the surface. The data processing system also includes a deviation determination module programmed to determine a point deviation for each of at least a portion of the plurality of surface points. The data processing further includes a deviation map module programmed to construct a deviation map, including a set of deviation regions for the surface. The deviation map module is also programmed to construct a graphical representation of the deviation map. The data processing system still further includes a graphical user interface for selective display of the graphical representation. The inspection system further comprises a marking station including an image transfer system in communication with the data processing system. The image transfer system may include a printing arrangement having a remotely controllable printing applicator. The printing arrangement may be configured for application of the graphical representation to the surface.
Other objects and advantages of the invention will be apparent to one of ordinary skill in the art upon reviewing the detailed description of the invention.